The present invention relates to a liquid crystal display panel of an active matrix type, and in particular, to a method of manufacturing an active matrix panel employing an amorphous silicon thin-film transistor.
Conventionally, an active matrix panel includes a thin-film transistor (TFT) having a structure described, for example, in the JP-A-60-189970 or JP-A-63-9977.
However, in the JP-A-60-189970, although the construction of the JP-A-60-189970 is identical to that of the present invention in a point that a channel protective film is consecutively formed so as to follow a gate insulation film and a semiconductor film, description has not been given of a reduction of the process step by employing a self-alignment in association with work of the respective layers. Based on the drawings thus disclosed, there are effected several operations of photolithography and hence there is required a long process, which leads to a problem of productivity.
Moreover, also in the JP-A-63-9977, the constitution is equal to that of the present invention in that the gate electrode and the pixel electrode are formed at the same time; however, an operation to remove a metal film disposed on the pixel electrode is simultaneously achieved when a work is conducted on the gate insulator film by use of the self-alignment. In consequence, a surface of the pixel electrode (transparent conductor film) is likely to be subjected to a quality change (to increase resistance) through various kinds of processing. Since the metal film on the pixel electrode also serves as a protective film, the removal of the metal film is desirably accomplished in a process to be effected as late as possible. Furthermore, the channel protective film is not successively formed in the structure of the thin-film transistor described in this article.
As described above, according to the prior art technology, considerations have not be given so as to produce the active matrix panel through a simple process with a high productivity. Development of the market of the liquid-crystal display can be achieved by a technology which enables a large amount of active matrix panels (to be simply referred to as a panel herebelow) to be produced at a lower cost. In consequence, improvement of the yielding in the panel production and minimization of the production process step have been essential problems to be solved. Although not described in the prior technologies above, the panel requires, in addition to the thin-film transistor portion, such functional units as a pixel electrode section, an additional capacity portion, a wiring intersection portion of double layer, and a terminal portion. For these functional sections, a lower conductor film, an upper conductor film, an insulation film, a semiconductor, a doped semiconductor containing impurity, and/or a protective film are/is required to be disposed if necessary.